Throughput and delay performance of IEEE 802.11e enhanced distributed channel access (EDCA) under saturation condition

In this paper, we analyze the saturation performance of IEEE 802.11e enhanced distributed channel access (EDCA), which provides contention-based differentiated channel access for frames of different priorities in wireless LANs. With EDCA, quality of service (QoS) support is provided with up to four access categories (ACs) in each station. Each AC behaves as an independent backoff entity. The priority among ACs is then determined by AC-specific parameters, called the EDCA parameter set. The behavior of the backoff entity of each AC is modeled as a two-state Markov chain, which is extended from Bianchi´s model to capture the features of EDCA. The differences of our model from existing work for 802.11e EDCA include: (i) virtual collisions among different ACs in an EDCA station are modeled, thus more accurately capturing the behavior of EDCA; (ii) the influence of using different arbitrary inter-frame spaces (AIFS) for different ACs on saturation performance are considered; (iii) delay and delay jitter are derived, in addition to saturation throughput. The analytical model is validated via ns-2 simulations. The results show that our analytical model can accurately describe the behavior of IEEE 802.11e EDCA